In today's commerce, merchants often utilize an array of different point-of-sale (POS) devices, including mobile POS devices. Merchants may use these mobile POS devices to engage in transactions with customers at different locations. For instance, a taxi driver may use a mobile POS device to charge a passenger for a taxi ride. In another example, a street vendor may use a mobile POS device to charge a customer for an item purchased from the street vendor. In some instances, these mobile POS devices are configured to operate in either an online mode or offline mode. In the latter instances, when an operator of a POS device “swipes” a payment instrument, information regarding the payment instrument and a corresponding transaction are stored locally on the POS device for later sending to a remote service for authorization of the payment instrument (after the POS device transitions back to the online mode).